Nec Corporation

Gold Charm Limited

Nec Corporation and Nec Electronics Corporation

Koichi Iguchi

Isao Sasaki

Katsumi Abe

Masamichi Shimoda

Shigeo Nishitoba

An image display apparatus comprises a pixel having a drive transistor and a pixel display element which are connected in series between a first power line and a second power line, a holding capacitor connected to a gate electrode of the drive transistor, and a selection transistor connected between a signal line and the gate electrode of the drive transistor. When the selection transistor is turned on, gradation pixel data is written in the holding capacitor from the signal line. The charge of gradation pixel data written in the holding capacitor is discharged for a certain period through the drive transistor, thereafter the charge of the gradation pixel data stored in the holding capacitor is held by floating the gate electrode of the drive transistor.

Image display apparatus and control method therefor

Image display and its control method

A current-control-type light emitting display in which a reverse current can be supplied to a light emitting element without requiring a negative power supply and without being passed through a forward drive section. A first electrode of the light emitting element is connected via a first switching device to a second power supply line set to 0 V, and is connected to a drive section via a second switching device. A second electrode of the light emitting element is connected to a third power supply line selectively connected to a voltage source from which an arbitrary positive voltage is supplied or another voltage source from which 0 V is supplied. A reverse current is supplied to the light emitting device by setting the potential on the first electrode of the light emitting element equal to the potential on the second power supply line and by setting the potential on the second electrode equal to the potential on the third power supply line from which an arbitrary positive voltage is supplied.

Circuit for driving light emitting element and current-control-type light-emitting display

A precharge circuit is provided with an N-channel transistor intended for switching. A reference potential is applied to either one of the source and drain of this N-channel transistor. The other of the source and drain is connected to a node. A precharge signal is applied to the gate of the N-channel transistor. The reference potential is set to a precharge output potential for the case of displaying black on a pixel, i.e., the potential when a minimum current flows through a P-channel transistor connected to the other of the source and drain of the N-channel transistor.

Driving circuit of current-driven device, current-driven apparatus, and method of driving the same

Drive circuits are incorporated in an active matrix image display apparatus and drive current-driven devices such as organic EL (electroluminescent) elements. Each of the drive circuits includes a drive transistor for driving the current-driven device and an auxiliary transistor connected parallel to the drive transistor and having a current driving capability which is n times the current driving capability of the drive transistor. In a portion (accelerated period) of a selected period, a drain current flows into the auxiliary transistor and a signal current flowing through a signal line, which represents a current to flow into the current-driven device, is (n+1) times a normal value. As a result, the effect of parasitic capacitors connected to signal lines is reduced, allowing the current-driven devices to be driven with an appropriate drive current even when signal currents are very small.

Circuit for and method of driving current-driven device

In a current driver circuit that is applicable to an organic EL (electroluminescent) image display device, the current driver circuit is provided for reducing the influence of variation between transistors that constitute a current mirror circuit while using the current mirror circuit. In the current driver circuit, a third and fourth transistor that operate in a linear region (non-saturation region) are provided between the power supply line and the sources of a first and second transistor that constitute the current mirror circuit; whereby the influence of variations between the threshold voltages of the first and second transistors can be mitigated. The gates of the third and fourth transistors are connected to the gates of the first and second transistors, respectively.

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Tokyo, Japan

Koichi Iguchi